Heat oil in a non-stick frying pan over medium-high heat. Add prawns. Cook for 1 to 2 minutes each side or until prawns turn pink. Remove to a board.
Add garlic and chilli to frying pan. Cook for 1 minute. Add tomatoes and 1/4 cup cold water. Cook, stirring occasionally, for 5 minutes or until softened. Chop prawns. Add prawns, basil and salt and pepper to tomato mixture. Stir to combine.
Spoon sour cream and prawn mixture over cooked jacket potatoes. Serve with lemon wedges.